[FFmpeg-devel] [PATCH 6/7] Implement if(expr, cond) binary function evaluation.

[Víctor Paesa]

Hi,

2010/11/1 V?ctor Paesa :
> Hi,
>
> On Mon, Nov 1, 2010 at 01:52, Stefano Sabatini wrote:
>> On date Monday 2010-11-01 01:22:48 +0100, Michael Niedermayer encoded:
>>> On Mon, Nov 01, 2010 at 12:23:32AM +0100, Stefano Sabatini wrote:
>
> [...]
>
>> "PTS=st(0, PTS); if(isnan(ld(0)), st(0,PREV_INPTS+k)); ld(0)"
>
> should be equivalent to
> "PTS=isnan(PTS)*PTS + eq(isnan(PTS),0)*(PREV_INPTS+k)"

Ahem, I really mean:
"PTS=isnan(PTS)*(PREV_INPTS+k) + eq(isnan(PTS),0)*PTS"

>> I know that this is ugly as an a####le but I can't conceive other
>> ways to express such an expression. while() could be used but would be
>> even uglier. Best solution would be to have an if(COND,EXPR,ELSEEXPR)
>> but this requires more work on eval.
>
> * works like AND
> + works like OR
>
> "if A then B else C"
> is equivalent to
> "A*B + not(A)*C"
>
> When A evaluates to either 1 or 0, that is the same as
> "A*B + eq(A,0)*C"

Regards,
V?ctor